Add a flag (-G) to aapt to have it output the classes that shouldn't be obfuscated by ProGuard.
diff --git a/tools/aapt/Command.cpp b/tools/aapt/Command.cpp
index 790b474..f2cdf75 100644
--- a/tools/aapt/Command.cpp
+++ b/tools/aapt/Command.cpp
@@ -233,7 +233,7 @@
     return -1;
 }
 
-static String8 getAttribute(const ResXMLTree& tree, const char* ns,
+String8 getAttribute(const ResXMLTree& tree, const char* ns,
                             const char* attr, String8* outError)
 {
     ssize_t idx = tree.indexOfAttribute(ns, attr);
@@ -1158,6 +1158,12 @@
         }
     }
 
+    // Write out the ProGuard file
+    err = writeProguardFile(bundle, assets);
+    if (err < 0) {
+        goto bail;
+    }
+
     // Write the apk
     if (outputAPKFile) {
         err = writeAPK(bundle, assets, String8(outputAPKFile));